Hands-on Science Sunday: Atmosphere model

by Stephanie Chasteen on May 17, 2009

I’m going to try posting a regular feature here on sciencegeekgirl — Hands-on Science Sunday.  I figure, if I were a teacher, Sunday might be the day I’d appreciate getting an idea of a science classroom activity.  So, here you go.  

Why do it?
This is a good activity to help your students visualize percentages (including really small percentages), as well as calculating ratios, all while learning more about the composition of the atmosphere and why carbon dioxide is so important.  You can adapt this activity to middle school, but I believe it’s more suitable to 9th-10th grade.

Materials:

  • Rice
  • clear plastic bottle
  • food coloring
  • digital scale
  • funnel

What to do

First, you’ll want to dye a bunch of rice different colors.  You’ll need 4 colors (plus white) — each color will represent one constituent of the atmosphere.  I found that sushi rice soaks up somewhat diluted food dye fairly well — here is an activity sheet on rainbow rice (PDF).  Tough to mess up, but messy all the same.  If you want to get fancy, you can buy black rice, but this quickly gets expensive.  In fact, because each atmosphere model uses a litersworth of rice, you will want to have students team up on this activity to reduce materials’ cost.

Then, using the percentages of the different constituents of the atmosphere, fill the bottle with those proportions of rice, using a scale.  (This is tricker than it seems, see the handout, below, for a good method to do this systematically).

  • 78% nitrogen
  • 21% oxygen
  • 2% water vapor
  • 1% argon
  • 0.04% carbon dioxide

Add the nitrogen and oxygen first and mix them up.  This gives you a good visual of what 78% and 21% mean, in terms of how the constituents are spread throughout the volume.  

Then throw in the water vapor and argon.

Wow.  It’s not very much.  But water vapor is a significant contributor to global warming.

Now put in 3/4 of the carbon dioxide grains.  That’s the earth’s atmosphere in 1880.

Now add the rest of the carbon dioxide.  Those are today’s levels.  So, why do we care so much about the increase in carbon dioxide in the atmosphere?  Because the rest of the atmosphere is transparent to the infrared.  Carbon dioxide “traps” infrared (because infrared light makes its bonds jiggle, so it sends some of that heat back down to earth).  

Shake up the bottle to mix up the grains.  Now see if you can find any of the argon, carbon dioxide, or water vapor, as you turn the bottle around.

You can see a bunch more activities from me and Paul on climate and weather here

This activity was written in collaboration with Paul Doherty at the Exploratorium.  See the full activity on his website.

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